One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,3,6,8,5,7)(9,10,13,16)(11,17,19,14)(12,15,20,22)(18,23,24,21)(25,26,29,33,30,28,31,34)(27,35,38,39,37,32,36,40)(1,3,5,2,6,7,4,8)(9,11,13,19)(10,14,16,17)(12,18,20,24)(15,21,22,23)(25,27)(26,32)(28,35)(29,38)(30,37)(31,36)(33,40)(34,39)(2,7)(3,8)(4,5)(12,20)(15,22)(18,24)(21,23)(25,28,30,26)(27,32,37,35)(29,33,31,34)(36,40,38,39)(2,8)(3,7)(9,12,13,20)(10,15,16,22)(11,18,19,24)(14,21,17,23)(25,29,30,31)(26,33,28,34)(27,36,37,38)(32,39,35,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.